In the present work, TIG and A-TIG welding were compared to show the arc constriction phenomena. A 2D axial symmetric model was developed to simulate the flow behavior in the melting pool. These results were compared to experiments carried out on a stainless steel disc (304L) melted by a stationary heat source. The influence of the Marangoni effect, arc constriction and type of flux is shown. The results point to the importance of the welding parameters and the use of a flux on the characteristics of the weld beads.